1. Field of the Invention
The present invention relates to an industrial two-layer fabric that does not collapse mesh openings at an interwoven position of a binding yarn, is excellent in rigidity, water drainability, wear resistance, and fiber supporting property, and exhibits uniform dehydration characteristics throughout the fabric.
2. Description of the Related Art
Fabrics obtained by weaving warps and wefts have conventionally been used widely as an industrial fabric. They are, for example, used in various fields including papermaking fabrics, conveyor belts, and filter cloths and are required to have fabric properties suited for the intended use or using environment. Of such fabrics, a papermaking fabric used in a papermaking step for removing water from raw materials by making use of the mesh openings of the fabric must satisfy a severe demand. For example, there is therefore a demand for the development of fabrics that have excellent surface smoothness and do not transfer a wire mark of the fabric to paper, have a dehydration property to sufficiently and uniformly dehydrate excessive water contained in the raw materials, have enough rigidity and wear resistance which enable suited use even under severe environments, and are capable of maintaining conditions necessary for making good paper for a prolonged period of time. In addition, they are required to have a fiber supporting property, improved papermaking yield, dimensional stability, running stability, and the like. In recent years, owing to the speed-up of a paper making machine, requirements for papermaking fabrics become severer.
Most of the demands for industrial fabrics and solutions thereof can be understood from a description on papermaking fabrics on which the most severe demand is imposed among industrial fabrics. A description will next be made with the papermaking fabric as an example.
With a recent increase in the speed of a papermaking machine, papermaking fabrics are required to have a particularly excellent dehydration property and surface smoothness. Although dehydration characteristics which they are required to have differ with the type of a papermaking machine or the type of a product to be manufactured, a uniform dehydration property is one of essential conditions for any product. Further, it becomes more difficult to satisfy the demand for papermaking fabrics because an increase in a mixing rate of minute fibers in raw materials as a result of recent increased use of waste paper causes insufficient dehydration so that sufficient and uniform dehydration has gained in importance.
As fabrics exhibiting a good dehydration property, there are two-layer fabrics having a dehydration hole penetrating through from the upper surface side to the lower surface side thereof. In particular, as fabrics designed to satisfy a surface property, fiber supporting property, and dehydration property which papermaking fabrics are required to have, two-layer fabrics using a warp binding yarn to be woven with an upper side weft and a lower side weft to form an upper side warp design and a lower side warp design, respectively, are known. Japanese Patent Laid-Open No. 2004-36052 discloses a two-layer fabric using a warp binding yarn. The fabrics of such related art are two-layer fabrics using some of warps as a warp binding yarn functioning as a binding yarn for weaving an upper side layer and a lower side layer. The warp binding yarn constituting a set complements an upper side warp design and a lower side warp design to form each of the surface designs so that fabrics thus obtained are excellent in surface property and binding strength.
Japanese Patent Laid-Open No. 2004-68168 discloses a two-layer fabric having a set of an upper side warp and a warp binding yarn with a view to achieving a uniform dehydration property. This fabric has a uniform design on the surface thereof by using an upper side knuckle of the warp binding yarn for weaving upper and lower surfaces and an upper side warp design in combination. This fabric is free of a collapse of the design because the above-described two warps cooperatively form a design corresponding to a single warp on the surface, but one of or both of the warps should collapse the design of the warp itself. They form a crossing portion when running between the upper side and the lower side and the warps constituting a first warp set is placed as a single warp. The two warps do not overlap each other along a line corresponding to a single warp but are arranged side by side so that the warp binding yarn clogs a mesh opening near the position where it is woven with an upper side weft. This causes a partial change in the dehydration characteristics of a wire and may transfer a mark to paper.
Such a two-layer fabric has, throughout the fabric, dehydration holes completely penetrating through from the upper side layer to the lower side layer so that it has a good dehydration property. Sheet raw materials on a wire stick to the fabric due to powerful vacuuming or the like or fibers, fillers, and the like are fallen from the wire, which may cause a marked increase in dehydration marks. As described above, industrial fabrics capable of satisfying any of the necessary properties such as surface property, fiber supporting property, and wear resistance have not yet been developed.